Nitro-pyrimidines

ABSTRACT

Compounds of the formula   WHEREIN R1 is selected from the group consisting of H and NO2, and R2, R3 and R4 are selected from the group consisting of H and   ARE PREPARED BY REACTING PICRYL BROMIDE WITH THE APPROPRIATE PYRIMIDINE OF THE FORMULA   WHEREIN R5, R6 and R7 are selected from the group consisting of H and halogen. These compounds are used as heat resistant explosives.

ilnite States atent n91 Sitzmann et a1.

[ 51 Dec. 2, 1975 1 NITRO-PYRIMIDINES [75] Inventors: Michael E. Sitzmann, Chevy Chase, Md.; Joseph C. Dacons, Washington, DC.

[73] Assignee: The United States of America as represented by the Secretary of the Navy, Washington, DC.

22 Filed: Oct. 4, 1972 [21] Appl. NO.Z 298,088

[52] 1.1.8. Cl. 260/251 R; 149/105 [51] Int. Cl. C071) 239/50 [58] Field of Search 149/105; 260/251 R [56] References Cited UNITED STATES PATENTS 7/1964 DeMaris 149/105 3,621,022 11/1971 Berger et al. 260/251 R Primary Examiner-Leland A. Sebastian Attorney, Agent, or FirmR. S. Sciascia; J. A. Cooke 57 ABSTRACT I Compounds of the formula wherein R is selected from the group consisting of H and N0 and R R and R are selected from the group consisting of H and are prepared by reacting picryl bromide with the appropriate pyrimidine of the formula wherein R R and R are selected from the group consisting of H and halogen. These compounds are used as heat resistant explosives.

5 Claims, N0 Drawings NITRO-PYRIMIDINES BACKGROUND OF THE INVENTION This invention generally relates to explosives and more particularly to explosives with excellent heat stability.

Use of explosives in many different types of devices is widely known in the prior art. However, despite the huge number of explosives that are known there are relatively few that can withstand high temperatures of at least 280C or above without substantial deterioration. Since explosives in many specialized uses are sub jected to temperatures of about 280C or higher there has been a constant search for explosive materials which will not deteriorate substantially due to high temperatures.

SUMMARY OF THE INVENTION Accordingly, one object of this invention is to provide new chemical compounds.

Another object of this invention is to provide chemical compounds that can be used as explosives.

A further object of this invention is to provide explosive compounds which are capable of withstanding temperatures of at least about 280C without substantial deterioration.

A still further object of this invention is to provide explosive compounds which can be used in environments wherein high temperatures are a problem (i.e., where aerodynamic heating is a problem).

Yet another object of this invention is to provide explosive compounds which can be used in mild detonating cord and flexible linear shaped charges.

These and other objects of this invention are accomplished by providing chemical compounds of the formula wherein R is selected from the group consisting of H and N and R R and R are selected from the group consisting of H and which are prepared by reacting picryl bromide or any picryl halide, with the appropriate pyrimidine of the formula O R1 N/LRG wherein R R and R are selected from the group consisting of H and a halogen.

DESCRIPTION OF THE PREFERRED EMBODIMENT Compounds of the formula wherein R, is H or NO and R R and R are H or are prepared by contacting a picryl halide, such as picryl bromide, with a pyrimidine of the formula wherein R R and R are H or halogen. This reaction is the typical, well known Ullman biaryl synthesis. The pyrimidine is dissolved in a solvent such as nitrobenzene and copper is added. The picryl halide is then added dropwise to the above solution over a period of about /2 hour and the temperature is maintained around 150C throughout. Following this the solutions are purified using typical purification techniques.

The general nature of the invention having been set forth, the following examples are presented as specific illustrations thereof. It will be understood that the invention is not limited to these specific examples but is susceptible to various modifications that will be recognized by" one of ordinary skill in the art.

EXAMPLE 1 PICRYL BROMIDE An amount of 355 g (3.5 moles) of reagent grade potassium nitrate was dissolved in 800 ml of 30% oleum in a 2000 ml 3-neck round bottom flask fitted with a mechanical stirrer and a thermometer. During the addition of the potassium nitrate, the mixture was cooled and stirred on an ice bath, the temperature being kept below 60C. When the addition was complete, the mixture was cooled to 30C and 79 g (0.5 moles) of bromobenzene was added at such a rate as to keep the temperature below 50C. The ice bath was then replaced by an oil bath and the reaction mixture was heated to approximately C for four hours. After cooling, the mixture was drowned in crushed ice, the product was collected by filtration using a sintered glass funnel and thoroughly washed with water. After drying in a warm oven, it was dissolved in l00 ml of acetone, 300 ml of methanol was added and the solution was cooled in the freeze compartment of the refrigerator. On filtration, 83.7 g of pale yellow crystalline picryl bromide, mp l20-l22C (lit. l22-3C) was recovered. The filtrate was concentrated to about ml by boiling on the steam bath and again cooled in the freeze compartment. The second crop weighed 28.0 g and melted over the range 111118C. On recrystallization from acetone-ethanol, an additional 21.0 g of crystalline product, mp 120122C was obtained to give a total yield melting at this temperature of 104.7 g, 71.6%. Samples melting at l22-123C were obtained by one additional recrystallization from acetone-methanol.

EXAMPLE 2 2, 4, 6 TRIPICRYLPYRIMIDINE 3neck A vigorously stirred mixture of 22.0 g 1.12 moles) of 2,4,6-trichloropyrimidine (commercially available) and 106.7 g (1.68 moles) of copper in 120 ml of nitrobenzene was heated to 145C in a 1000 ml 3-neck round bottom flask equipped with a mechanical stirrer, a thermometer and an addition funnel. A solution of 140.2 g (0.48 moles) of picryl bromide in 210 ml of nitrobenzene was added over a period of 25 minutes. During the addition and for five minutes thereafter, a temperature range of 145-150C was maintained. The reaction mixture was then cooled to 70C and stirred into 1300 ml of methanol. After cooling to 10C, the mixture was filtered, the solid residue was washed with methanol and digrested in 1200 ml of aqueous HCl at 5060C to remove the copper salts. After filtering and washing with dilute l-lCl, water and finally methanol, the dark brown residue on the funnel was dissolved in 280 ml of dimethylsulfoxide at 100C. The solution was treated with 35 g of activated charcoal. The solution was then filtered and the charcoal pad was washed with 75 ml of hot dimethylsulfoxide. A volume of 1500 ml of methanol was slowly added to the filtrate to precipitate the product. On cooling to 10C, filtering and washing with methanol, 52.6 g of a tan product which partially melted at ca 230C, resolidified and melted finally at 335340 C was collected. This product, which was a solvate, was dissolved in 175 ml of nitrobenzene at 175 C. The solution was allowed to cool to room temperature, filtered, and the cream colored crystalline product was thoroughly washed with methanol. After drying in a warm oven, the product weighed 43.3 g, partially melted at 230C and melted finally at 3412 C (dec). An additional crop of 8.1 g obtained from the filtrate showed similar melting characteristics except that its final melting point was 337.9 C. Both crops were combined and recrystallized from 155 ml of nitrobenzene. The yield was 45.6 g of yellow crystals which melted the same as the first crop above. After drying under vacuum at 145-150 C for 4.5 hours, 38.9 g (45.4%) of a cream colored crystalline product, m.p. 34l2 C (dec) was recovered.

EXAMPLE 3 2,4-DIPlCRYL-S-NITROPYRIMIDINE A vigorously stirred mixture of 5.28 g (0.03 moles) of 2,4-dichloro-5-nitropyrimidine (prepared by the procedure of N. W. Whittaker, J. Chem. Soc, 1565-70 (1951)) and 17.6 g (0.28 moles) of copper in 20 ml of nitrobenzene was rapidly heated to 145 C in a 100 ml 3-neck around bottom flask equipped with a mechanical stirrer, a thermometer and an addition funnel. A solution containing 23.4 g (0.08 moles) of picryl bromide in 40 ml of nitrobenzene was added dropwise over a period of minutes. The temperature range of 145-150 C was maintained during the addition and for five minutes thereafter. The dark brown mixture 4 was then cooled to C and stirred into 500 ml of methanol. The mixture was cooled to 10 C, filtered and the solid residue was digested in 400 ml of 20% HCl HC at 6070 for 10 minutes to remove the copper salts. The residue was recovered by filtration, and after washing with dilute HCl, water and finally methanol, it was dissolved in 50 ml of dimethylsulfoxide by heating to C. The dark brown solution was treated with activated charcoal, filtered and the charcoal pad was washed with a small amount of hot dimethylsulfoxide. The product was precipitated by adding 300 ml of methanol and cooling in an ice bath. On filtration, 9.25 g of light brown crystals, m. p. 3256 C (dec) were recovered. This product was recrystallized by dissolving in 60 ml of nitrobenzene at 180 C, and cooling to room temperature. The yellow crystalline product was recovered by filtration and washed with methanol. On drying, it weighed 8.0 g and melted with decomposition at 3278 C. An additional 0.95 g (same melting point) was obtained by adding 150 ml of methanol to the mother liquor. The total yield was 8.95 g (54.6%).

EXAMPLE 4,6-DIPICRYL- 5-NITROPY RIMIDINE A vigorously stirred mixture of 23.3 g (0.12 moles) of 4,6-dichloro-S-nitropyrimidine (commercially available) and 71.1 g (1.12 moles) of copper in ml of nitrobenzene was rapidly heated to C in a 500 ml 3neck round bottom flask fitted with a mechanical solid residue was removed by filtration and washed,

with methanol. The residue was extracted by stirring in 1500 ml of boiling acetone and the mixture was filtered while hot. The filtrate was treated with 20 g of activated charcoal and filtered. The filtrate was then concentrated by rapid distillation with stirring until considerable crystallization had occurred and the volume was about 250 ml. Methanol was then added at about the same rate as the distillate was removed until the temperature of the distillate was 62 C. Approximately 500 ml of methanol was required. The mixture was then cooled to room temperature, filtered, and the cream colored crystalline product was washed with methanol. On drying, the product weighed 31.0 g (47.3%) and melted at 349350 C with decomposition. An additional crystallization did not improve the melting point of the product and reduced the yield only slightly to 30.6 g (46.7%).

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described herein.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. Pyrimidines of the formula wherein R is selected from the group consisting of H d N0 d R R d R1 are Selected from the group 4. The compound of claim 1 wherein R is N0 R is consi ti f H d H and each of R and R are "z N 2 N -0 2. The compound of claim 1 wherein at least 2 of R R3 and R4 are 5. The compound of claim 1 wherein R is N0 R is 2 H and each of R and R are N O N v Q N N02 3. The compound of claim 1 wherein R is H and each of R R and R are 

1. PYRIMIDINES OF THE FORMULA
 2. The compound of claim 1 wherein at least 2 of R2, R3 and R4 are
 3. The compound of claim 1 wherein R1 is H and each of R2, R3 and R4 are
 4. The compound of claim 1 wherein R1 is NO2, R3 is H and each of R2 and R4 are
 5. The compound of claim 1 wherein R1 is NO2, R4 is H and each of R2 and R3 are 